The present invention relates to a paper making machine. More particularly, the present invention relates to a paper making machine including a wet paper layer forming portion.
Paper making machines of the Fourdrinier and cylinder types have primarily been heretofore employed in the paper making industry. These machines, however, have the common drawback that the manufactured paper sheets tend to curl in the transverse direction and that the entire machine tends to be enlarged in scale. For example, in the Fourdrinier paper making machine, a paper material slurry is supplied onto an endless elongated forming fabric through stock inlets at substantially the same speed as the moving speed of the elongated forming fabric, and the primary dehydration of the paper material slurry is conducted at a horizontal portion of the moving elongated forming fabric by the effect of gravity and by suction of suction boxes. In recent years, the elongated forming fabric has been operated at higher speeds for the purpose of improving productivity. For this reason, the following drawbacks have resulted. There is caused a speed differential between the elongated forming fabric and the paper material slurry supplied thereto, the direction of orientation of the fibers in the material slurry inevitably tending to be directed in the direction of movement of the elongated forming fabric, whereby the paper sheets after manufacture curl in the transverse direction. Further, in keeping with the acceleration of the paper manufacturing speed, the dehydration section must be made increasingly longer. Consequently, the length of the horizontal portion of the elongated forming fabric must be increased, and the overall machine thus becomes larger. Furthermore, the suction box is made to contact the inner surface of the elongated forming fabric during the suction and dehydration processes, whereby the frictional force between the suction box and the elongated forming fabric represents a load which not only increases the quantity of power consumed, but also causes abrasion of the elongated forming fabric, thereby shortening the life thereof. These defects cause the manufacturing cost of the paper to be increased. What is worse, substantial noise pollution is caused by the operation of a number of suction boxes.